15436( 3) - 18-Dec-2017 17:25:14 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 15436 Version: 3 Check-in Time: 18-Dec-2017 17:25:14 STScI Edit Number: 1 Title Understanding the Origin of Large Gas Reservoirs in Recently-Quenched Galaxies ------------------------------------------------------------------------------------ Type Cycle GO 25 ------------------------------------------------------------------------------------ Investigators Contact? PI: Ms. Katherine Suess University of California - Berkeley Y CoI: Dr. Justin Scott Spilker University of Texas at Austin N CoI: Dr. Rachel Bezanson University of Pittsburgh N CoI: Prof. Mariska Kriek University of California - Berkeley N CoI: Prof. Jenny Emma Greene Princeton University N ------------------------------------------------------------------------------------ Abstract The physical mechanisms that quench star formation, turning disky star-forming galaxies into quiescent elliptical galaxies, remain hotly debated. Post-starburst galaxies present a fascinating laboratory in which to study how star formation is suppressed, especially at z>~0.5 when these galaxies can be identified immediately after their primary star-forming epoch. We recently detected large molecular gas reservoirs in massive post-starburst galaxies at z~0.7 with ALMA-- much more gas than expected given their SFR. However, to fully interpret these remarkable ALMA results we must understand the roles of highly obscured star formation and merging in these galaxies. Here, we propose to use the VLA to obtain 1.4GHz-based SFRs for our three ALMA targets; these data are essential to determine whether these objects are truly as quiescent as they appear. Non-detections would prove that these objects are among the least efficient known star-formers. We also have hints that mergers may be important in quenching these galaxies, but existing imaging does not resolve the galaxies: we therefore propose to use complementary HST imaging to study the morphology of these galaxies and search for merger signatures. Obtaining both VLA and HST data will also allow us to place these galaxies on the classical Kennicutt-Schmidt relation. ------------------------------------------------------------------------------------ Observations Description ------------------------ For each of three z~0.6 bright post-starburst galaxy targets (i_AB ~ 15) we will perform a one-orbit observation of about 50 minutes. Each integration will be divided into five on-source integrations, plus 10 minutes for acquisition and dithers. We will take four dithers using the WFC3-IR-DITHER-BOX in order to properly sample the PSF. To maximize our dynamic range, we will use STEP50 with NSAMP=15. We take an additional exposure using STEP50 and NSAMP=15 at our last dither position to fill the orbit. The 10.6 min of overheads are divided into 6 min of acquisition, 0.3 x 4 for dithers, and 0.8 min of readout per exposure. We will observe with the WFC3-IR/F110W filter. For the given exposure time, we will reach a surface brightness in F110W_AB of 25.9 (at 5sigma) in an aperture of 5 by 5 pixels. Given an average total magnitude of 19 and an approximate scale length of 0.4", we derive that we will observe the galaxies out to 3-4 scale lengths. With radial binning we will 15436( 3) - 18-Dec-2017 17:25:14 - [ 2] reach ~2 magnitudes deeper. ------------------------------------------------------------------------------------ 15436( 3) - 18-Dec-2017 17:25:14 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 SDSSJ0912+15 GALAXY, ELLIPTICAL, RA=09H12M42.7704S, J2000 Z = u_AB = 20.91 +/- 0.09, g_AB = 20.37 23 LENTICULAR, STARBURST, DEC=+15D23'5.25" 0.747 +/- 0.03, r_AB = 19.59 +/- 0.02, i_AB = UNDESIGNATED 18.64 +/- 0.01, z_AB = 18.40 +/- 0.03 Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ2202-00 GALAXY, ELLIPTICAL, RA=22H02M24.2904S, J2000 Z = u_AB = 21.99 +/- 0.19, g_AB = 20.75 33 LENTICULAR, STARBURST, DEC=-00D33'34.39" 0.657 +/- 0.03, r_AB = 19.38 +/- 0.02, i_AB = UNDESIGNATED 18.54 +/- 0.01, z_AB = 18.25 +/- 0.03 Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 3 SDSSJ0027+01 GALAXY, ELLIPTICAL, RA=00H27M25.4406S, J2000 Z = u_AB = 22.01 +/- 0.28, g_AB = 20.95 29 LENTICULAR, STARBURST, DEC=+01D29'57.90" 0.585 +/- 0.05, r_AB = 19.26 +/- 0.02, i_AB = UNDESIGNATED 18.57 +/- 0.01, z_AB = 18.32 +/- 0.04 Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 15436( 3) - 18-Dec-2017 17:25:14 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-IR-DITHER-BOX-MIN Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 1.420 Line_Spacing 0.919 Coordinate_Frame POS-TARG Pattern_Orient 17.370 Angle_Between_Sides 76.301 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 15436( 3) - 18-Dec-2017 17:25:14 - [ 5] Visit: 01 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 SDSSJ0912+1 WFC3/IR MULTIAC IR F110W NSAMP=15, SAMP-SEQ=STEP50 1 DEF PATTERN 1 1 523 CUM (1996.937 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ0912+1 WFC3/IR MULTIAC IR F110W SAMP-SEQ=STEP50, NSAMP=15 1 DEF 523 CUM (499.234 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ0912+1523 1 WFC3/IR MULTIAC IR F110W 1 none none none 1 N/A CUM SDSSJ0912+1523 1 WFC3/IR MULTIAC IR F110W 2 none none none 1 N/A CUM SDSSJ0912+1523 1 WFC3/IR MULTIAC IR F110W 3 none none none 1 N/A CUM SDSSJ0912+1523 1 WFC3/IR MULTIAC IR F110W 4 none none none 1 N/A CUM SDSSJ0912+1523 2 WFC3/IR MULTIAC IR F110W none none none none 1 N/A CUM 15436( 3) - 18-Dec-2017 17:25:14 - [ 6] Visit: 02 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 SDSSJ2202-0 WFC3/IR MULTIAC IR F110W NSAMP=15, SAMP-SEQ=STEP50 1 DEF GS ACQ SCENARIO BASE1B3; 033 CUM (1996.937 PATTERN 1 1 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ2202-0 WFC3/IR MULTIAC IR F110W SAMP-SEQ=STEP50, NSAMP=15 1 DEF 033 CUM (499.234 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ2202-0033 1 WFC3/IR MULTIAC IR F110W 1 none none none 1 N/A CUM SDSSJ2202-0033 1 WFC3/IR MULTIAC IR F110W 2 none none none 1 N/A CUM SDSSJ2202-0033 1 WFC3/IR MULTIAC IR F110W 3 none none none 1 N/A CUM SDSSJ2202-0033 1 WFC3/IR MULTIAC IR F110W 4 none none none 1 N/A CUM SDSSJ2202-0033 2 WFC3/IR MULTIAC IR F110W none none none none 1 N/A CUM 15436( 3) - 18-Dec-2017 17:25:14 - [ 7] Visit: 03 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 SDSSJ0027+0 WFC3/IR MULTIAC IR F110W NSAMP=15, SAMP-SEQ=STEP50 1 DEF PATTERN 1 1 129 CUM (1996.937 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ0027+0 WFC3/IR MULTIAC IR F110W NSAMP=15, SAMP-SEQ=STEP50 1 DEF 129 CUM (499.234 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ0027+0129 1 WFC3/IR MULTIAC IR F110W 1 none none none 1 N/A CUM SDSSJ0027+0129 1 WFC3/IR MULTIAC IR F110W 2 none none none 1 N/A CUM SDSSJ0027+0129 1 WFC3/IR MULTIAC IR F110W 3 none none none 1 N/A CUM SDSSJ0027+0129 1 WFC3/IR MULTIAC IR F110W 4 none none none 1 N/A CUM SDSSJ0027+0129 2 WFC3/IR MULTIAC IR F110W none none none none 1 N/A CUM 15436( 3) - 18-Dec-2017 17:25:14 - [ 8] Summary Form for Proposal 15436 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures IR ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/IR ------------------------------------------------------------------------------------------------------------------------------------ Opmodes MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters NSAMP=15, SAMP-SEQ=STEP50 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements GS ACQ SCENARIO BASE1B3, PATTERN 1 1 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F110W ------------------------------------------------------------------------------------------------------------------------------------ Target Names SDSSJ0027+0129, SDSSJ0912+1523, SDSSJ2202-0033 ------------------------------------------------------------------------------------------------------------------------------------